lib/unistr/u8-mbsnlen.c

   1 /* Count characters in UTF-8 string.
   2    Copyright (C) 2007, 2009-2021 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2007.
   4
   5    This program is free software: you can redistribute it and/or modify it
   6    under the terms of the GNU Lesser General Public License as published
   7    by the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #include <config.h>
  19
  20 /* Specification.  */
  21 #include "unistr.h"
  22
  23 size_t
  24 u8_mbsnlen (const uint8_t *s, size_t n)
  25 {
  26   size_t characters;
  27
  28   characters = 0;
  29   while (n > 0)
  30     {
  31       ucs4_t uc;
  32       int count = u8_mbtoucr (&uc, s, n);
  33       characters++;
  34       if (count == -2)
  35         break;
  36       if (count < 0)
  37         count = u8_mbtouc (&uc, s, n);
  38       else if (count == 0)
  39         count = 1;
  40       s += count;
  41       n -= count;
  42     }
  43   return characters;
  44 }